STEVENS POINT - While her two Republican foes trade verbal blows in the closing days of a fiery primary battle, Democratic U.S. Sen. Tammy Baldwin has been quietly touring Wisconsin.

At farms, bars, restaurants and village halls, Baldwin has discussed issues such as rural broadband and the opioid crisis and listened to local voters, activists and business leaders.

It's all part of what she calls the "In Your Corner Tour," an eight-day campaign trip through 18 counties.

And while it might seem like political small ball, it's the sort of tour an incumbent senator does to reach out to various parts of the state ahead of what will likely be a rugged re-election campaign in the fall.

Baldwin doesn't yet know who her opponent will be — Delafield businessman Kevin Nicholson or state Sen. Leah Vukmir of Brookfield — but she's setting a political table and honing a message.

With the U.S. Senate August recess shortened, Baldwin has crammed in as many events as she can before heading back to Washington, D.C., next week.

On Wednesday, she chaired a discussion on clean drinking water at the Schmeeckle Reserve Visitor Center, part of a natural area on the University of Wisconsin-Stevens Point campus.

She said there has been a real attack on clean water programs at the federal level.

"It has been my responsibility as well as my honor in restoring those funds," she told more than a dozen people. Groundwater contamination is a concern here, especially for rural residential well owners.

Baldwin hasn't ceded the campaign field to Vukmir and Nicholson. She has put together a ground game for the general election with 50 paid field organizers and 200 neighborhood teams of volunteers.

Over the months, her campaign has spent $5 million on TV ads, focusing on local issues as well as "Buy America" legislation to push for U.S.-made steel and iron in water infrastructure projects.

And in her campaign speeches, she has pushed back against "powerful special interests" who are trying to take her out with millions of dollars in spending.

Nearly $18 million in outside spending has flooded the race, including $4.2 million against Baldwin and $1 million to support her, according to the Center for Responsive Politics. Among the big spenders: Illinois businessman Richard Uihlein who backs Nicholson and the Koch brothers political network.

Baldwin has proven to be an adept fundraiser. Since winning election to the Senate for the first time in 2012, she has raised $21 million.

She told the Journal Sentinel that she is focused on "listening to Wisconsinites and the issues they care about."

"I have a strong feeling that the November race will boil down to being a race about who is fighting for Wisconsinites and hearing their concerns and focusing their attention on working on those as opposed to sidling up with the special interests and to try to do their bidding in Washington."

Baldwin said that "in an ideal world, without campaign finance run amok," her work in the U.S. Senate alone "would be paving the way for a successful campaign."

The first negative ads against her ran more than a year ago and Baldwin said "we got pretty serious, this is where we are now."

July's Marquette University Law School Poll found her viewed favorably by 41% of registered voters and unfavorably by 40%.

Asked if she sensed there might be a blue wave for Democrats in the fall, Baldwin said there was enthusiasm but "I will tell you, the only wave I've seen in Wisconsin these days is a green wave and I'm talking about the cash coming in from the Koch brothers ... Richard Uihlein."

She said the response to that cash is "a common sense wave. People have witnessed some pretty crazy things these days, dysfunction in Washington that results in an inadequate focus on the needs of working people in this state. And then all this spending to try and make that seem like it's normal."

"I think we're going to see some people just with common sense say we're going to get involved, stay involved," she said.

Republicans are poised for the fall campaign. Alec Zimmerman, a spokesman for the Republican Party of Wisconsin, said: “Tammy Baldwin’s far-left record in D.C. couldn’t be further from her rhetoric on the campaign trail. From voting in favor of higher taxes, to supporting government-run health care, to her failures to stand up for veterans at the Tomah VA, Baldwin has picked Washington over Wisconsin time and again."

Paul Maslin, a Democratic pollster, said Baldwin has sought to "establish the element she wants to run on," emphasizing that she is "closer to the voters in Wisconsin" on issues of health care, education and the economy.

Maslin works with Senate Majority PAC, an outside group working to help elect Baldwin and other Democrats running for Senate. He said Baldwin has shown she "can work across party lines to get things done."

The Cook Political Report rates the Wisconsin race as "likely Democrat," even though President Donald Trump won the state in 2016.

"Yes, it's a state that Trump carried but he carried it by a point. It's not like West Virginia that he carried by 42 points," said Jennifer Duffy, senior editor of the Cook Political Report.

Duffy said the GOP primary has given Baldwin "time to put together an organization, start talking message, pretty much unimpeded."

"At the same time, the general election might get more competitive," she said. "We'll see. I think there are differences of opinion on who would give her a tougher race. I think there is going to be a lot of outside money in the race, especially on the Republican side. It's one of these things, I'm just kind of waiting to see what the eventual nominee can do."

Duffy said of all the competitive U.S. Senate races in the country, "this is probably the least developed."